Method of making motor compressor units



1946. F. RATAICZAK 2,405,904

METHOD OF MAKING MOTOR COMPRESSOR UNITS [Original Filed May 28, 1941 4 Sheets-Sheet 1 3 if A F. l. RATAICZAK METHOD OF MAKING MOTOR COMPRESSOR UNITS Original Filed May 28, 1941 4 Sheets-Sheet 2 INVENTOR.

Aug. 13, 1946. I F. 1. RATAICZAK 2,405,904

METHOD OF MAKING MOTOR COMPRESSOR UNITS Aug. 13, 1946.

F. I. RATAICZAK 'ME'YIHOD OF MAKING MOTORTQOMPJRESSOR UNI'rs '4 SheetS-Sheet 4 Original Filed May 28, 1941 A I T I? Patented Aug. 13, 1946 2,405,904 METHOD OF MAKING MOTOR COMPRESSOR UNITS Francis I. Rataiczak, Dayton", Ohio, assignor to.

General Motors Corporation,,Day.ton, Ohio, a-

corporation of Delaware Original application May 28, 1941, Serial No.

UNITED STATES PATENT OFFICE 395,645. Divided and this application'Deccm-ber 11,1942, Serial No. 468,615

7 Claims. 1

This invention relates to refrigerating apparatus and more particularly to animproved motorcompressor unit for use in a refrigerating system.

This application is a division of my co-pending application Serial No'. 395,645, filed May 28, 1941.

One of the objects of this invention is to provide a mass production method of making a motor-compressor unit.

Another object of this invention is to provide a method of manufacturing and assembling a.

motor-compressor unit in which errors in alignment may be detected during assembly of the motor-compressor parts without the use of complicated checking equipment.

Still another object of this invention is to provide a method of manufacture which makes it possible to reduce the amount of material used in a. motor-compressor unit.

A further object of this invention is to simplify the assembly of the motor-stator within the motor-compressor housing.

Further objects and advantages of the present Fig. 5 is an enlarged sectional view showingthe.

suction valve assembly;

Fig. 6 is an elevational view of the maincasing without the heat radiating fins and witha-portion of the casing broken awayso asto .more clearly show the motor stator mounting means;

Fig. '7 is a planview of the main casing and. the motor-stator and illustrates the .manner in which the main compressor casing is inserted through the motor-stator;

Fig. 8 is an elevational view partly in section showing the apparatus used for aligning themain compressor cylinder with the motor-stator; and

Fig. 9 is a. fragmentary elevational view, withparts broken away, illustrating the apparatus for aligning the main compressor bearing with the motor-stator.

In the-manufacture of motor-compressor. units,

2 it is customaryr and; in fact, necessaryto -tolerate small errors in thedimensionsand'concentricity of various. elements; Inthe ordinary" motorcompressordesigtn the accumula'tionof tolerances; materially afiects the'efliciency of the. unita'and.

frequently renders the. unit? completely inoperative, in which case, it: becomes necessary to reoperate: some of; the: parts. or to match certain parts with other ipartsin which thedimensional errors balance out upon. assembly; Thistis especially true in case the .compressorrand its; associated. motor-rotor is assembled with. avst'atorwhich is not perfectly concentric. with the'main.

bearing due to. tolerances necessary in the-manufacture of the stator or dueto 'a; slight error in themanufacture of thest'ator mountingmeans...

or dueto an accumulation oferrorsinthezmotorstator and its .mounting' means.

Referring now to. Fig; luof the: drawings in which I haveshown a preferred embodiment: of my invention, reference numeral. 10' designates generally a hermetically sealed motor-compressor unit: Reference numera'l i2i designates arsu'bstantially cup-shaped stampedsheetmetal casing which forms the main 'supportifor the compressor assembly l4 and also the motor-stator" l'6..

Reference numeral. l8 .designatesra:v conventional motor-rotor; Astamped. sheet metal end cap' I! close the upper end. of the cup sh'aped casing elementv I 2: and forms therewith a high'pressure refrigerant'vapor chamber. The end :cap 11" is welded or otherwise secured to the main casing I2. Heat. conducting finsv 2 I. may besecuredto the outside of the casing element I2 to help-dis-- sipate the heat. The high pressure-gas flows to the condenser: 20: inwhich it is-condensed and collects in liquid. phase in the receiver 22. The

liquid refrigerant flows from the receiver 22 into-- the evaporator 24 through a conventional re frigerant flow control device 26,. The refrigerant flow control devicemay be of any conventional eonstruction and is preferably of the fixed restri'ctor type in which the high pressure liquid refrigerant is required to flow through along narrow capillary passage.

The refrigerant vaporized in the-evaporatorreturns to the compressor through thedine 28' which communicates with a passage 30 formed in the adapter block 32. A screen element 34 i arranged directly within thepa-ssage- 30*and serves to stop the flow of solid particles intothe main compressor. As best shown in- Fig. 5, the upper side of the adapter block 32 is provided with arecess 36 in which a check valve, generally designated by the reference numeral 38' blocks 39 which are weldedorotherwise secured Th upper to the bottom Wall of the casing I2. surfaces of the blocks 32 and 39 are machined so as to be perpendicular to the motor-stator support surfaces described hereinafter. The stamping 44, in turn, holds the valve element 40 in place. By virtue oflthis arrangement no.

is cut away as at 92 so as to provide a passage from the high pressure refrigerant chamber to the passage 90 and the passage 88. The outer ends of the passages 86 and 88 are sealed by means of a plug 94 and a lead-plated copper gasket 96. The gasket 96 is provided with apertures 98 in alignment with the passages 86 and 88. The plug 94 is provided with a single passage I through which refrigerant and/or lubri- 'cant' may be added to or removed from the refrigerant system upon partially unscrewing the plug' 94. By virtue of this arrangement, both the high sideand the low side of the refrigerating system may be very quickly evacuated prior special fastening means is required and in them event of valve failure, the damaged valvepart amount of difficulty.

.Asbest shown in Fig. 1, the compressor assembly. I4 comprises a lower end plate 50, a. cylinder element 52 and an upper end plate 54 which has formed integrally therewith the main bearing 55;. The upper end plate 54, as shown in Fig. 3, carriesa conventionaldischarge valve assembly .58 which controls the flow of refrigerantzthrough the compressor outlet 60. provided in the end plate 54. .An impeller 62 is provided within. the cylinder 52. vvThe impeller 62 is mounted on the eccentric 64 which causes the impellertocompressxthe refrigerant in accordance with well-known practice.

Apdivider-block 6B cooperates with the cylinder 52-?9J1d "the impeller 62 in accordance with wellknown practice. A spring 68 biases the divider block into engagement with the impeller 62.. The outer end of the sprin rests against the spring retainer .10.;The retainer I0, as shown in Figs. 2 and3iis provided with a pair of arms I2 having bent end portions which interlock with the holes. lfiidrilled-in the cylinder element 52. The spring retainer .zl0zis slipped into place-before the cyl-. inderiZ-is clampedbetween the end plates 50 andidandiis held in place by the end plates 50 an'd I. v

i-The end plate 50 is providedwith a tapered passage 18: which. conveys the low pressure refrig'erant:vap0r from the inlet valve 38 to the compression chamber 80. By virtueof the taper in; the walls of the passage I8, any slight misalignment between the end plate 50 and the inlet valve ;.38 will. not interferewith the free flow of-refrigerant from the inlet valve to the compression chamber.

Referring to Fig. 2,;it will be observed that the inlet port, I8 enters the compression chamber 80 at a point close to but. spaced from the divider blockffi and spaced from the inner wall o'fqthe cylinder element 52. It will also be observed that pressure relief notches 82 have been provided in the cylinder wall 52 adjacent the divider :block 66. By virtue of the inlet port arrangement, the inlet port is completely closed during the final portion of the compression stroke with the resultv that it is impossible for any of the compressed gas remaining in the pressure; relief-cavity to reexpand into the intake port -.,The adapter block 32 is provided with a refrigerantcharging plug 84 which has a first passa-ge sfi communicating with the compressor inlet passage '30 and a second passage 88 communie eating with a passage 90in the adapter block;

3:2: I.'h elower end plate 150 of the compressor of specialclamps such as I02. or parts may be replaced with a mmimum to charging the system with refrigerant and lubricant;

Themotor-stator I6 is held in place by means The clamps I02 are initially formed as shown in Fig. 6, and are spot welded or otherwise secured to the shell I2. In the prior art devices, it is customary to provide a pressfit between the outer shell of the compressor and the motor-stator. In such an arrangement, it is very difiicult to properly hold the motor-stator in place unless a very heavy cast ironframe or the equivalent is used; and once the motor-stator is in place, it is very diificult to remove it forinspection or repair purposes. By virtue of the clamping arrangement shown, a light weight sheet metal casing may be used and the final sizing operation may be performed merely by forcing a die of proper size into the opened end of the'casing so as to deform the projecting portion I04 of each clamp I02 the necessary amount. This arrangement of parts and method of sizing eliminates the necessity for turning the inner surface of the outer shell I2 to size on a lathe. Furthermore, the clamping elements I02 serve to compensate for any taper or irregularity in the walls of the shell l2. It is difficult to form the outer sheet metalcasings to any exact dimension since the strains and stresses in the sheet metal casing produced by the drawing operation tend to distort the walls of the casing. The clamps I02, however, sufiiciently compensate for such distortions.

After the motor-stator has been inserted in place,- the projecting ends I06 of the clamp elements I02 are bent over onto the upper side of the motor-stator so as to hold the motor-stator in a fixed position. This not only reduce the cost of construction and facilitates the assembly of the apparatus, but also facilitates the removal of the motor-stator in the event that it becomes necessary to replace the motor-stator. The lower ends of the clamps I02 are provided with ears I01 which limit the downward movement of the motor-stator. v

The cover member I! is provided with fitting IIO, through which the compressed refrigerant leaves the unit I0. The fitting IIO serves as a stop for limiting the axial movement of the motor-rotor I8 and the shaft I9 during shipment, etc. Duringnormal operation, the shaft I 9 is spaced from the adapter H0 as shown in Fig. 1.

In order to avoid the harmful accumulationlof tolerances in dimensions in assembling the various parts, the various part of the unit are assembled in the following manner. In assembling the various elements that'goto make up the compressor unit, the first step is to position the cylinder 52 with respect to. the lower end wall 50. This is .doneby means of a conventional positioning mandrel (not shown) which holds the member 52 in proper alignment with the member 56 while one or more bolts-such as bolt I50 (see Fig. 3) is or are tightened'so as to clamp the-elements 56 and 52 together in their proper relationship. After the element 56 and 52 have been-fastenedtogether in proper alignment, the impeller 62, the divider block 66, the divider block spring-68 and the spring retainer '16 are inserted in place and the upper end plate 56 is bolted to "the cylinder 52 and the lower end plate-'56 by means of bolts 51. A positioning mandrel (not shown) i used for holding the end plate '54 in alignment while the bolts5'I are being tightened.

The compressor assembly may-then be inserted downwardly through the opening inthe motor-stator as shown in Fig.1 The compressor assembly i's-of such shape and size that it may readily pass through the opening in the motorstator. After the compressor assembly has been slipped into place in the bottom of the casing I2, a specially constructed positioning fixture I52 is used for aligning the main compressor bearing with the inner surface of the motor-stator.

'The positioning fixture I62 comprises a central shaft I56 provided with a knurled handle I66. The main portion of the central shaft I54 has a diameter corresponding to the internal diameter of the main compressor bearing55. Another portion I68 of the central haft I64 has a diameter slightly less than the internal diameter of the impeller 62. The lowermost portion I60 of the'central shaft I56 has a diameter corresponding to the internal diameter of the bearing 26 provided inthe lower end plate 56 for the lowermost portion 23 of the main compressor shaft IS. The positioning fixture I52 has an intermediate sleeve member I62 which is slidably mounted on the central shaft I54. The intermediate sleeve I62 is provided with a knurled handle portion I64. The lower end of the sleeve I62 i tapered for a purpose explained hereinafter. The main body I66 of the positioning fixture I52 has a central aperture through which the sleeve I62 and the shaft I54 may be inserted. The outer diameter of the main portion of the element I66 is slightly less than the internal diameter of the motor-stator I6.

As best shown in Fig. 9, the main body I66 of the positioning fixture is provided with four longitudinally extending slots I68 in each of which is mounted a hoe element I16. Each shoe element I is provided with a shank I12 which passes through a radially extending hole I1 3 formed in the body I66. The inner end of each shank is provided with a cam surface I16 which is adapted to engage the tapered portion of the sleeve I62. The element I66 is provided with a shoulder I18 which limits the movement of the element I66 within the motor-stator I6. The arrangement is such that when the positioning fixture is inserted into the motor-stator and the sleeve element I62 is moved into the position in which it is shown in Fig. 8, the sleeve I62 cams the shoes I16 into engagement with the motor-stator, whereby the central shaft I5 1 of the positioning mandrel may be used for lining up the compressor assembly with respect to the motor-stator.

The main body I66 of the positioning fixture is provided with a plurality of apertures I 86 through which access may be had to the cap screws 56 which secure the compressor assembly to the mounting blocks 32 and 39. While the positioning fixture is in place, the cap screws 56 are securely tightened so as to rigidly hold the compressor assembly in position. After having ,6 tightened the cap-screws 56, the positioning man drel'i removed. By removing the sleeve I 64, the-shoes I16 release their hold'on the -vvall's=of the motor-stator whereby the mandrel 'may' be removed without di'fiiculty.

In the event that the upper "surfaces of the block 39 and the adapter element 7 32 arenot perpendicular to the inside walls of'thetmotor-stator, the positioning mandrel will bind when the cap screws '56 are tightened. This serves to give notice that the proper perpendicularity is lack ing'so that the compressor assemblymay be immediately removed and the parts reoperatedso as to obtain the proper perpendicularity. After removal of the positioning mandrel I52, the' motor-rotor I8 and its associated shaft I9 maybe dropped into place.

Inasmuch as theabove described construction allows the motor-rotor to'besecured'to theshaft Il'prior to the assembly of the shaftin' thermain bearing; it is possible to true-up the outerdiameter of the motor-rotor afterithas been mounted on the shaft, thus eliminating'the accumulation of tolerance in the concentricity of the main shaft, the internal .bore of the 'motor ro-tor and the external diameter of the motor-rotor.

While the forin of embodiment of thelinvention as herein disclosed, constitutes a preferred form, it is to be understood that other forms might be adopted, all coming within the scope of the claims which follow.

'What is claimed is asfollows:

l. The method of manufacturing a motorcompressor unit which comprises forming a substantially cup-shaped casing, securing motorstator mounting means to the inner-wall of the cup-shaped casing, forcing a sizing die within said motor-stator mounting means so as to deform said mounting means so as to establish a motor-stator receiving opening of proper size, forming compressor mounting surfaces adjacent the bottom of said casing perpendicular to the motor-stator mounting surfaces, positioning a motor-stator on said motor-stator mounting surfaces, passing a compressor assembly through the central opening of said motor-stator, positioning the compressor assembly on said compressor mounting surfaces by means of a positioning fixture, clamping said compressor assembly in fixed relationship to said compressor mounting surfaces while being held by said positioning fixture, removing the positioning fixture, and thereafter inserting a compressor operating shaft and motor-rotor.

2. The method of manufacture which comprises forming a housing element having a. substantially cylindrical inner-surface, securing motor-stator mounting means to the inner-wall of said cylindrical housing member, forcing a sizing die into said cylindrical housing member so as to partially compress and deform said motorstator mounting means, removing said sizing die, and thereafter assemblying the motor-stator within said housing element in engagement with said mounting means.

3. The method of positioning a compressor bearing assembly in concentric relationship to a motor-stator having an inner cylindrical surface which comprises, positioning the compressor bearing assembly with the bearing surfaces in concentric relationship to the inner cylindrical surface of said motor-stator by mean of a removable positioning fixture having a first portion for engagement with said compressor hearing assembly and having a second concentric portion in engagement with said motor-stator, securing said compressor bearing assembly in fixed relationship with said motor-stator while thus positioned and thereafter removing said positioning fixture and assembling the compressor operating shaft and motor-rotor.

. 4. The method of manufacture which comprises forming a substantially cup-shaped casing, forming motor-stator mounting surfaces on the inner wall of the cup-shaped casing, forming compressor mounting surfaces adjacent the bottom of said casing arranged perpendicular tosaid motor-stator mounting surfaces, positioning a motor-stator on said motor-stator mounting surfaces, passing said compressor assembly through the central opening of said motor-stator, positioning the compressor assembly on said compressor mounting surfaces, clamping said compressor assembly in fixed relationship to said compressor mounting surfaces, thereafter assembling a compressor operating shaft and motor-rotor by passing the compressor operating shaft through the central opening of said motor-stator, and

thereafter securing a closure member to the open end of said cup-shaped casing.

5. The method of manufacture which comprises forming a substantially cylindrical housing member, forming motor-stator mounting surfaces on the inner-wall of said housing member, and thereafter positioning a motor-stator on said motor-stator mounting surfaces, securing a bearing element in fixed relationship with said housing member while held in concentric relationship with respect to the inner surface of said motorstator by means of a removable positioning fixture and thereafter supporting a motor-rotor assembly 8 in said bearing with the motor-rotor disposed within said motor-stator.

6. The method of manufacturing a motor-compressor unit which comprises stamping a substantially cup shaped casing, welding sheet metal motor-stator mounting means to the inner wall of said casing, sizing the motor-stator engaging surface of said mounting means by swaging any irregular internal marginal surfaces, welding motor-stator mounting block means to the bottom wall of said casing, machining the upper surfaces of said block means perpendicular to said motorstator mounting surfaces, forcing a motor-stator in place within said motor-stator mounting means, securing a compressor assembly on said machined surfaces in axial alignment with said motor-stator, and thereafter inserting a compressor operating shaft and motor rotor.

7. The method of manufacturing a motorcompressor unit which comprises forming a substantially cup-shaped casing with motor-stator mounting surfaces on the inner wall of said casing and compressor mounting surfaces adjacent the bottom of said casing, sizing the motor-stator mounting surfaces by swaging any irregular internal marginal surfaces, machining the compressor mounting surfaces perpendicular to said motor-stator mounting surfaces, forcing a motorstator in place relative to said motor-stator mounting surfaces, securing a compressor assembly on said machined surfaces in axial alignment with said motor-stator, and thereafter inserting a compressor operating shaft and motor rotor down through said motor-stator.

FRANCIS I. RATAICZAK. 

